Ah, that's actually a natural side effect of bilinear texture filtering. Textures get switched to a lower-resolution mipmap when they're far away, and they look blurry when viewed at a low angle like that. For the best texture quality at all viewing positions, you can select anisotropic filtering. If you want the textures to look as they did in the original game, you can set the filtering mode to "None (classical)" (which actually uses a mode called nearest-neighbor filtering).